April 2010
Volume 51, Issue 13
ARVO Annual Meeting Abstract  |   April 2010
Rod Visual Responses in the Absence of Rod -Transducin
Author Affiliations & Notes
  • R. J. Lucas
    Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
  • M. A. Cameron
    PMRI, Royal North Shore Hostpital, University of Sydney, Sydney, Australia
  • A. E. Allen
    Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
  • T. M. Brown
    Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
  • Footnotes
    Commercial Relationships  R.J. Lucas, None; M.A. Cameron, None; A.E. Allen, None; T.M. Brown, None.
  • Footnotes
    Support  Wellcome Trust, BBSRC, University of Manchester Alumni Fund
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 1665. doi:
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      R. J. Lucas, M. A. Cameron, A. E. Allen, T. M. Brown; Rod Visual Responses in the Absence of Rod -Transducin. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1665.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : Photoreception is mediated by outer-retinal rod and cone photoreceptors, and melanopsin-expressing retinal ganglion cells. Gnat1-/- Cng3a-/- Opn4-/- (triple knock-out) mice lack critical elements of the phototransduction cascades associated with each of these mechanisms, via specific ablation of the rod transducin alpha-subunit, cone cyclic nucleotide gated channel, and melanopsin gene. Although assumed blind, these mice retain a small, transient pupillary light reflex. This led us to investigate whether other visual responses are also retained in this genotype and, if so, what photoreceptor drives them.

Methods: : Flash ERGs were recorded from wild type and triple knock-out mice under dark adapted conditions and against a rod-saturating background light (2.6 log10 µW.cm-2). Light-dependent changes in spike-firing rate were assessed via multi-electrode recordings in the pretectum and thalamus of anaesthetised triple knock-out mice.

Results: : We report a low amplitude but highly reproducible flash ERG in triple knock-out mice, indicating relatively widespread light-evoked activity in retinal neurons. This response originates in the outer retina, and has a spectral sensitivity matching that of rod opsin. In vivo recordings of neurons within retino-recipient areas also reveal light-evoked increases in firing rate.

Conclusions: : Here we have identified an array of visual responses downstream of an α-transducin independent mechanism of phototransduction that is active in rod photoreceptors.

Keywords: photoreceptors • electroretinography: non-clinical • electrophysiology: non-clinical 

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